Knowing unique lines and how there are variables between how long the line is, and some pokemon introduced in later gens are continuations of previous lines, I've reduced them to simply unique lines and calculated the same thing.

First calc: how many unique lines introduced in a generation appear in Galar vs the total amount of unique lines per generation.

I've calculated this based on the FIRST TIME a pokemon from a unique line appears. So, for example, even though Roselia has 2 of its line debut in gen 4, I'm counting it as a Gen 3 line. I've EXCLUDED legendaries and fossils from the initial TOTAL unique line statistic, seeing as NO fossils or previous legendaries (save mew) have returned. I've INCLUDED starter lines based solely on the Charmander line appearing (meaning there was "potential" for all other starter lines to return). Percentages are calculated based off this number.

*mew is technically a legendary but is the only exception to no legendary rule
**counting phione/manaphy and cosmog >>>> solgaleo/lunala as 1 line each

This final crunch examines how much from each gen make up of the total unique lines returning (and for fun, doing a comparative percentage based off what I'm calling the "potentiality" of lines returning. So, the total unique lines by gen that are viable for Galar dex representation against the TOTAL amount that are viable, just to see if the percentages are different).

Using data in the previous spoiler, I crunched the # of unique lines by the total unique lines in gen 8. The percentage in the bracket shows the comparative unique line ratio that calculates ALL unique lines per generation against TOTAL unique lines in pokemon that would've been viable for gen 8 (325), to compare if the percentages are about the same.

to no one's surprise, gen 5 has the most representation.
The PERCENTAGE of gen 5 rep by individual pokemon is nearly double any other two generations combined.
Gen 4 has the least representation, but proportional to gen 4's quirk of more or less being a means to flesh out previous existing lines, the percentage of potential representation (8.9) vs ACTUAL representation (7.9) is comparable. By contrast, gen 5's POTENTIAL (16.3) compared to ACTUAL (27.6) is quite boosted.

I've been wondering how each type was affected by Dexit (as in, what percentage of each type's Pokemon are left out). Someone would have to crunch the numbers, but just eyballing it, it looks like Water and Ghost made out great, Fire and Poison not so good, and Normal got absolutely nuked. But like I said, that's just from a quick glance and could be wrong.

I've calculated this based on the FIRST TIME a pokemon from a unique line appears. So, for example, even though Roselia has 2 of its line debut in gen 4, I'm counting it as a Gen 3 line. I've EXCLUDED legendaries and fossils from the initial TOTAL unique line statistic, seeing as NO fossils or previous legendaries (save mew) have returned. I've INCLUDED starter lines based solely on the Charmander line appearing (meaning there was "potential" for all other starter lines to return). Percentages are calculated based off this number.

*mew is technically a legendary but is the only exception to no legendary rule
**counting phione/manaphy and cosmog >>>> solgaleo/lunala as 1 line each

Using data in the previous spoiler, I crunched the # of unique lines by the total unique lines in gen 8. The percentage in the bracket shows the comparative unique line ratio that calculates ALL unique lines per generation against TOTAL unique lines in pokemon that would've been viable for gen 8 (325), to compare if the percentages are about the same.

to no one's surprise, gen 5 has the most representation.
The PERCENTAGE of gen 5 rep by individual pokemon is nearly double any other two generations combined.
Gen 4 has the least representation, but proportional to gen 4's quirk of more or less being a means to flesh out previous existing lines, the percentage of potential representation (8.9) vs ACTUAL representation (7.9) is comparable. By contrast, gen 5's POTENTIAL (16.3) compared to ACTUAL (27.6) is quite boosted.

Possibly the less representation of Sinnoh pokémon added to the fact that no mon from Sinnoh has Galarian Form or Gigantamax/Dinamax (Also Garchomp didn't make it :( ) maybe they want to tell us something about a great Sinnoh remake next time! :D

Possibly the less representation of Sinnoh pokémon added to the fact that no mon from Sinnoh has Galarian Form or Gigantamax/Dinamax (Also Garchomp didn't make it :( ) maybe they want to tell us something about a great Sinnoh remake next time! :D

I was pretty stunned at the lack of Sinnoh representation, but the last calc I did was the potentiality of Sinnoh lines being represented if all unique lines were taken into account, and it's actually pretty comparable (out the potentiality of 325 viable lines eligible to return in Galar, 8.9 were from Sinnoh -- what we are actually seeing out of 152 ACTUAL returning lines, 7.9 percent are from Sinnoh) so that actually clears some stuff up. Now i haven't crunched the comparisons of national dexes with each other, but I'm sure that would be an interesting statistic to take into account!

So I am not sure if anyone mentioned this, but why is Melmetal and family not in this dex? Wasn't it supposed to be a new pokemon for 8th gen? Why bring them in just for Lets go and not the new game? I really think there are more pokemon in the game just not shown in the pokedex yet.

EDIT: Greninja'd lol So really I am sure there will be a bunch more pokemon then whats just shown. Plus, we don't know what the post game is right? that normally adds a lot of older pokemon

I've been wondering how each type was affected by Dexit (as in, what percentage of each type's Pokemon are left out). Someone would have to crunch the numbers, but just eyballing it, it looks like Water and Ghost made out great, Fire and Poison not so good, and Normal got absolutely nuked. But like I said, that's just from a quick glance and could be wrong.

Fire: Arcanine, Ninetales, Flareon, Torkoal, Heatmor, Cinderace.
Fire with dual typing: Charizard, Salazzle, Turtonator, Coalossal, Centiskorch.
The dreaded Fire/Fighting type was a blessing for them. On paper they are really not looking so good, but only on paper.

So I am not sure if anyone mentioned this, but why is Melmetal and family not in this dex? Wasn't it supposed to be a new pokemon for 8th gen? Why bring them in just for Lets go and not the new game? I really think there are more pokemon in the game just not shown in the pokedex yet.

EDIT: Greninja'd lol So really I am sure there will be a bunch more pokemon then whats just shown. Plus, we don't know what the post game is right? that normally adds a lot of older pokemon

Penguin is my new favourite Gen 8 mon. I wonder how the different formes are going to be connected, a unique ability or an outside factor? For some reason they still included Delibird along with it, though this looks more like a real penguin and Delibird is more spiky.

I think the fact that Mew is colored green may not be from the leaker's dex specifically, and just based off the highly probable speculation.